A hybrid vehicle may include an internal combustion engine and an electric machine. The internal combustion engine and the electric machine may be selectively operated to propel the vehicle and recover the vehicle's kinetic energy during deceleration and vehicle braking conditions. The torque demands for the engine and the electric machine may be based on a base strategy that seeks to increase driveline efficiency so that energy consumed by the vehicle is reduced. However, the hybrid vehicle may not perform as is desired under all operating conditions when engine torque and electric machine torque are determined with a primary focus on driveline efficiency.
The inventors herein have recognized the above-mentioned issues and have developed an operating method for a hybrid vehicle, comprising: receiving input to a controller; and maintaining an engine torque and adjusting an electric machine torque via the controller in response to a driving maneuver based on the input and in further response to a decrease in a driver demand torque, the driving maneuver being expected to last less than a threshold duration based on the input.
By maintaining engine torque or adjusting engine torque to a value closest to engine torque immediately before a decrease in driver demand torque, it may be possible to provide the technical result of improving hybrid vehicle performance. For example, an engine that includes a turbocharger and variable valve timing may not respond as quickly as is desired to an increase in driver demand torque following a decrease in driver demand torque because it may take seconds for the valve timing to change and the turbocharger to reach a speed where a desired engine air flow is provided. However, engine torque may be maintained at or near engine torque before the decrease in driver demand torque while still providing the driver demand torque in combination with the electric machine. Specifically, engine torque may be maintained or adjusted to a torque near the engine torque before the decrease in driver demand torque by increasing magnitude of negative electric machine torque while the engine operates. The magnitude of electric machine torque may be decreased after a driving maneuver to make a large amount of engine torque available almost immediately. In this way, hybrid vehicle performance may be improved so that a driveline torque production is not delayed after performing a maneuver, such as negotiating a road turn in a vehicle.
The present description may provide several advantages. Specifically, the approach may reduce driveline torque production hesitation. In addition, the approach may be selectively applied so that energy consumption remains low during less aggressive driving. Further, the approach may be applied to both parallel and serial hybrid drivelines.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.